from random import choice
import matplotlib.pyplot as plt


class RandomWalk():

    def __init__(self, num_points=5000):
        # 初始化随机漫步的步数
        self.num_points = num_points

        # 初始化随机漫步的起点是（0，0）

        # 不断循环直到指定长度   self.x_values = [0]
        #         self.y_values = [0]
        #
        #     def random_walk(self):

        while len(self.x_values) < self.num_points:
            # 决定前进的方向以及沿这个方向前进的距离
            x_direction = choice([1, -1])
            x_distance = choice([0, 1, 2, 3, 4])
            x_step = x_direction * x_distance

            y_direction = choice([1, -1])
            y_distance = choice([0, 1, 2, 3, 4])
            y_step = y_direction * y_distance

            # 拒绝原地踏步
            if x_step == 0 and y_step == 0:
                continue

            # 计算下一个点的坐标值
            next_x = self.x_values[-1] + x_step
            next_y = self.y_values[-1] + y_step

            self.x_values.append(next_x)
            self.y_values.append(next_y)


while True:
    rw = RandomWalk()
    rw.random_walk()
    # 给点着色,颜色映射
    points_numbers = list(range(rw.num_points))
    plt.scatter(rw.x_values, rw.y_values, c=points_numbers, cmap=plt.cm.Blues,
                edgecolor='none', s=10)

    # 突出起点和终点
    plt.scatter(0, 0, c='green', edgecolor='none', s=50)
    plt.scatter(rw.x_values[-1], rw.y_values[-1], c='red', edgecolor='none', s=50)

    # 隐藏坐标轴
    plt.axes().get_xaxis().set_visible(False)
    plt.axes().get_yaxis().set_visible(False)

    plt.show()

    keep_running = input('Make another walk?(y/n):')
    if keep_running == 'n':
        break
